ML20216F412

Provides Comments on Draft RG DG-3013, Nuclear Criticality Safety Stds for Fuels & Matl Facilities. Guidance Found to Be Useful in Clarifying Some Staff Positions W/Respect to Interpretation of 10CFR70,Section 70.20

ML20216F412
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant, Paducah Gaseous Diffusion Plant
Issue date:	03/11/1998
From:	Toelle S UNITED STATES ENRICHMENT CORP. (USEC)
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
RTR-REGGD-XX.XXX GDP-98-0024, GDP-98-24, NUDOCS 9803180376
Download: ML20216F412 (2)

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1. USEC

^' W A Global Energy Company March 11,1998 i

GDP 98-0024 Chief, Rules and D ectives Branch

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Division of Administrative Services Mail Stop T-6 D59 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 j

i Paducah Gaseous Diffusion Plant (PGDP)

Portsmouth Gaseous Diffusion Plant (PORTS)

Dockei Nos. 70-7001 and 70-7002 j

USEC Comments on Draft NUREG-3013 (January 1998)

Dear Sir:

1 On behalf of the United States Enrichment Corporation (USEC),I am pleased to provide comments on Draft NUREG-3013, " Nuclear Criticality Safety Standards for Fuels and Material Facilities." In general, USEC found this guidance useful in that it clarifies some staff positions with respect to their interpretation of 10 CFR Part 70, Section 70.20. There were some areas where further clarification j

would be helpful and these are identified in the following comments on the Draft Reguireg Guide.

1. The statement contained in the first paragraph of the document, "Sectimt 76.35(4) states that the r

application for an initial certificate of compliance must establish teclatical safety requirements l

for preventing a nuclear criticality accident" appears to be incorrect. Section 76.35(4) does not I

contain this statement.

2. The statement regarding the demonstration of the safety margins relative to the bias and critically parameters needs to be revisited. While a validation report should seek to identify the inherent bias in the calculational method and tne range of applicability of the calculation method, it is generally not possible in a validation report to &monstrate the adequacy of safety margins. To y

determine a safety margin, a safety analysis is needed, whereby process parameters and specific controls are identified and safety limits established. (Safety margins are generally given by the margin between the safety limits for process variables and/or controlled parameters and the value

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at which these parameters establish a critical system. That is, a safety limit may be expressed g

as x cm for a given system, which becomes critical at y cm and therefore the resulting safety margin is y-x cm. The selection of the margin between the critical system and safety limit is generally a function of the robustness of the control system (s) utilized to fulfill the double 9003180376 980311 PDR ADOCK 07007001 R

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, i b' A 6903 Rockledge Drive. Bethea, MD 2 317-1818 Telephone 301-564-3200 Fax 301-564-K0; attp://www.usec.com O$ces in Livermore, CA Paducah, KY Portsmoeth, OH Washington, DC g i? M

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Chief, Rules and Directives Branch l

March 11,1998 l

GDP-98-0024, Page 2 '

contingency principle.) It should be noted snat the ANSI /ANS Standard 8.1 suggest that an additional margin of subcriticality be provided to ensure safety. This arbitrary margin of suberi'.icality will not in general present an equivalent margin of safety for different fissile systems. (For more detail on this see LA-12808, Tables 22-24 in the Appendix.)

3. Regarding the requirement of two criticality detectors; what is the basis for requiring two criticality alarm detectors when the ANSI committee has suggested that a single reliable detector is adequate?

4. Regarding the tabulated mass limits in ANSI /ANS-8.7 marked by an "a;" the selection of percentages of critical experiments should be based on a documented formal safety analysis l

which takes into account the robustness of the controls utilized to prevent an inadvertent nuclear i

criticality. Consequently, the arbitrary rejection of those tabulated mass limits marked with an "a" is deemed unwarranted.

5. The wording on page 5, paragraph 1 "could not result in a criticality" should be revised to reflect the required level of protection deemed unacceptable to the Nuclear Regulatory Commission.

l Suggested rewording "may be utilized only if double contingency has been adhered to."

If there are questions concerning these comments, please contact Dr. Marc Klasky at (301)S64-3408.

l Sincerely,

/1 5. A.

Ij Steven A. Toelle i

Nuclear Regulatory Assurance & Policy Manager e-.ng yrmn ce;;NRC Region HIig 1

NRC Resident Inspector - PGDP NRC Resident inspector-PORTS

~ NRC Special Projects Branch,NMSS j

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